I've dodged the bullet for now.
 

Had a bad leak in the A/C system in the 400E, 85K. All I can think about is the evaporator fun thing, so I did the next best thing and put a can of 134 stop leak in the system. Before, the system was losing it's charge in 2 days,,,, it's been a week now and still no bubbles in the sight glass and plenty of cold air. We'll see how long it holds and it has a dye in it so if the leak does reappear, maybe I'll be able to pinpoint it.

O rings are probably shrunk from using R134a oil. Look for oily residue on the connections at the evaporator, receiver/dryer, and compressor manifold.

The o-rings on the compressor itself on the TE have gone bad, same cause I believe.

Peter